The present invention relates to a cigarette manufacturing machine with a tobacco particle separator. On cigarette manufacturing machines, shredded tobacco is usually fed through an input feedbox to a bin inside which a carding unit feeds the tobacco into a down-flow duct. The bottom end of the said down-flow duct is usually connected to a well from which there extends upwards an up-flow duct the top end of which is closed off by a conveyor belt permeable by air. The tobacco from the said down-flow duct is usually deposited on to the said conveyor belt by means of suction exerted through the belt itself.
The suction exerted through the said conveyor belt is usually sufficient for forcing up, along the said up-flow duct, lighter tobacco particles consisting of dust and relatively minute shreds, whereas any lumps and/or woody particles drop down by force of gravity into the said well.
As only a small percentage of the material dropping into the well actually consists of waste material, all manner of attempts have been made, on known cigarette manufacturing machines, to separate the waste from the reclaimable material inside the said well, and to feed the reclaimed material back up along the said up-flow duct. For this purpose, extremely complex wells have been devised, inside which, air jets, differing in force and direction provide for unraveling any lumps, and for feeding any reclaimed lighter particles back up along the up-flow duct.
Known cigarette manufacturing machines of the aforementioned type present both structural and functional drawbacks.
In fact, the extremely complex structure of the well not only impairs reliability, but also results in inconsistent separation of the light and heavy tobacco particles inside the well itself, such separation depending on a relatively large number of parameters relating to the type and condition of the tobacco involved. For example, the damper the tobacco is, the poorer separation will be, in that damp tobacco tends to cling to the underside of the said permeable conveyor belt, thus minimising suction along the said up-flow duct and, consequently, also the force exerted for feeding back up the lighter particles separated inside the well. Consequently, any material failing to be fed back up along the up-flow duct, and which is therefore rejected by the machine usually comprises, not only the heavier tobacco particles, but also varying amounts of lighter particles, depending on the nature of the tobacco involved.